I am using the Verizon 3G Network Extender - which is a Femtocell. If you have a third party booster I agree there should be no difference from how it operates today...
I hate to say it, but my problem wasn't the Droid3. It turned out that I left my original Droid on without changing its MIN and MDN, and it was confusing the tower. Once I turned off the Droid, my Droid 3 started working perfectly.
To make sure this isn't your problem, dial ##7764726 on your old phone and hit send. SPC password is 000000 (this seems to be the same password on every VZW phone I've tried), go into User Activation and change the MIN and MDN. Don't worry about messing up your phone, *228 would fix it if you want to use it again.
I hate to say it, but my problem wasn't the Droid3. It turned out that I left my original Droid on without changing its MIN and MDN, and it was confusing the tower. Once I turned off the Droid, my Droid 3 started working perfectly.
To make sure this isn't your problem, dial ##7764726 on your old phone and hit send. SPC password is 000000 (this seems to be the same password on every VZW phone I've tried), go into User Activation and change the MIN and MDN. Don't worry about messing up your phone, *228 would fix it if you want to use it again.
For those with the Network Extender and still have your old phone, this is the fix that worked for me. I was frustrated by getting only 1x on my D3 when sitting next to my Network Extender. After I read this post, I turned off my D1 and low and behold...3G all day all night. Thanks neonerz!